The present invention relates to vacuum producing devices and, in particular, to devices having a restrictive venturi throat that cooperates with a suction tube and pressurized conduit.
A vacuum producing device according to the prior art is shown in FIG. 1. There a suction tube 10 is coaxially mounted within housing 12, whose downstream end has a restrictive throat 14 communicating with a flared duct 16. A blower conduit 18 is connected at right angles to the axis of the throat 14. In a well known fashion, restrictive throat 14 produces a vacuum in tube 10. An inefficiency in the prior art design involves the necessity for turning the blower air leaving conduit 18 90.degree.. This relatively sharp turn produces turbulence and unnecessary losses that reduce the energy available for suction through tube 10.
The vacuum producing device of FIG. 1 can be used for various purposes. One such purpose is to remove trim from plastic rolls as they are being cut to size. A blower cannot be directly connected to a suction hose that removes trim, since the trim would enter the blower and clog its impeller blades. By using a venturi as shown in FIG. 1, the trim travels along tube 10 and never enters the blower. The flared duct 16 can be connected by a pipe or other means to a bag or a container with air permeable walls to collect trim leaving tube 10.
Other known vacuum producing devices used a relatively straight vacuum line with a jet inlet at the vacuum line at an acute angle to the vacuum line. These known device were used to move materials such as grain or sand for sand blasting. Those devices did not, however, centrally locate a vacuum line within a housing aligned with a restrictive throat and flared duct to cause efficient material handling.
Known vacuum producing, venturi or related devices are shown in U.S. Pat. Nos. 3,100; 28,980; 351,854; 542,864; 688,049; 992,144; 1,116,971; 1,604,271; 1,612,838; 1,615,909; 1,686,713; 1,806,287; 1,942,048; 2,077,043; 2,111,266; 2,130,385; 2,297,681; 2,446,729; 2,584,326; 2,711,683; 2,722,372; 2,937,802; 2,951,457; 3,119,294; 3,152,839; 3,276,821; 3,378,309; 3,515,437; 3,747,738; 3,853,079; 4,253,610; 4,367,989; 4,850,752; and 4,936,031.
Accordingly, there is a need for an improved vacuum producing device that is more efficient and avoids other disadvantages of the prior art.